A so-called single-chip imaging apparatus, which is one kind of full color imaging apparatus, is applied in order to reduce the structure and manufacturing costs of an imaging apparatus, such as a household digital still camera or a mobile phone with a camera. In the single-chip imaging apparatus, color filters for red (R), green (G), and blue (B) are provided on the corresponding photo-electric conversion elements and the sensitivity signal of an insufficient color component is calculated for the position of each pixel, thereby obtaining the image signals of a plurality of colors from one two-dimensional imaging device. The sensitivity level value of the insufficient color component is generated by an interpolation process using the known sensitivity level values of a pixel of attention and the peripheral pixels thereof.
In order to generate the sensitivity level value of the insufficient color component, for example, a method has been used which extracts a low-frequency component and a high-frequency component from the image signal and adds the extracted frequency components. The addition of the high-frequency component makes it possible to prevent the deterioration of resolution and thus obtain a high-resolution image subjected to a pixel interpolation process. The correlation among RGB color components is a precondition for the interpolation process. For example, the correlation may not be established in the vicinity of the edge of the image due to the aberration of a lens or blurring. The interpolation process involving the breaking of the correlation is called zipper noise, which causes a dotted-line-shaped noise which is absent in the object.